1. Technical Field
This invention relates to securement clamps for switch point roller assist devices and, more particularly, to a rail flange securement clamp for adjustably mounting a switch point roller assist apparatus on a railroad rail which includes a base plate, a top plate generally upwardly spaced from the base plate, an adjustable connection extending between and connecting the base plate and top plate for increasing and decreasing the distance between the base plate and top plate and a rail flange engagement plate having a base section and rail flange engagement section, the plate adjustably mounted on the clamp above the top plate such that the base section of the plate is mounted above the top plate and the rail flange engagement section extends outwardly from the top plate for engagement of a flange of a railroad rail thereby securing a switch point roller assist apparatus on a railroad rail.
2. Description of the Prior Art
Railroad switching devices usually comprise tapered metal blades or tongues which set alternative routes of running rails. The term "turnout" is also used to denote a curved track leading from one track to another which takes place at a switching point. The commonest form of switch is the split switch in which one rail of the main track and the outer rail of the turnout are continuous. The point rails are connected respectively to the second rail of the main track and the inner rail of the turnout. The switch operates in the following manner: when the point rail connected to the second rail of the main track is in contact with the outer rail of the turnout, a locomotive traveling on the main track will continue on the main track; when the point rail connected to the inner rail of the turn out is in contact with the first rail of the main track, a locomotive traveling on the main track will be switched over to the turnout. The point rail is spaced such that in no circumstances can both point rails be in contact with an adjacent rail of the main track of the turnout.
To switch the point rails from contact with one rail of the main track to contact with the outer rail of the turnout and vice versa, both hand-operated and power-assisted switches are used. However, in both types of switches, the tapered ends of the point rails rest on a flat metal plate over which the ends of the point rails are slid. It is desirable to substantially reduce the friction between the tapered ends of the point rails and the flat metal plate from which they rest. Various devices have been proposed and constructed which remove the point rails from contact with the metal plate or the point rails are being moved, yet return the point rails to contact with the metal plate upon being moved into correct position.
One such device for assisting movement of the point rails is a switch point roller assist device manufactured by various companies. Such roller assist devices commonly include an elongated main support structure, a tie bar mounted generally perpendicular to the main support structure at one end of the structure, a clamping device for securing the opposite end of the main support structure to the outer flange of a railroad rail and one or more rollers rotatably mounted on the main support structure generally perpendicular thereto. The rollers are intended to lift the point rail slightly above the metal plate such that the point rail may be slid across the rollers.
Many of the problems encountered in using such switch point assist roller devices are found in the clamping device which secures the outer end of the main support structure to the flange of the railroad rail. Commonly, a switch point assist roller device would include an extended C-channel main support section having a longitudinally extended slot formed in the base of the C-channel adjacent the outer end of the main support structure. A standard clamping device for securing the C-channel main support structure to the flange of the railroad rail would consist of a flange engagement plate having a lower flange engagement face at one end of the plate and a bolt hole at the opposite end of the plate. A bolt would extend through the longitudinally extended slot in the C-channel main support structure and through the bolt hole in the flange engagement plate. The flange engagement face of the plate is slid over the upper slanted surface of the rail flange and the bolt is tightened down, thus securing the rail flange between the C-channel and the flange engagement plate. Because of the sloping upper surface of the rail flange, however, and because the rail flange plate is only secured to the C-channel by a single bolt, over a period of time the flange securement plate slides off of the flange and the switch point roller assist device loses contact with the rail flange. The switch point roller assist device thus becomes ineffective for lifting the point rails for ease of movement. There is therefore a need for an improved clamping device for securing the outer end of the main support structure to the flange of the railroad rail.
Therefore, an object of the present invention is to provide an improved clamping device for securing the outer end of the switch point roller assist device to the flange of a railroad rail.
Another object of the present invention is to provide a rail flange securement clamp which includes a base plate and a top plate for "sandwiching" the main support section of a switch point roller assist device, adjustable connection bolts for drawing the base plate and top plate towards one another to frictionally secure the plates on the main support structure and a rail flange engagement plate for securing the rail flange between the engagement plate and the switch point roller assist device.
Another object of the present invention is to provide a rail flange securement clamp which will frictionally engage the main support structure in addition to frictionally engaging the flange of the railroad rail to prevent slippage of the securement clamp off of the rail flange.
Another object of the present invention is to provide a rail flange securement clamp which may be quickly and easily adjusted to secure the switch point roller assist device in a particular location on the railroad rail such that the switch point roller assist device may more efficiently operate.
Another object of the present invention is to provide a rail flange securement clamp which may be used in connection with variously shaped and sized switch point roller assist devices.
Finally, an object of the present invention is to provide a rail flange securement clamp which is relatively simple and durable in construction and is safe and efficient in use.